PROJECT SUMMARY While the rate of neonatal abstinence syndrome has reached a staggering 6.5 per 1,000 births nationwide, the short- and long-term effects of opioid exposure are far from clear. We lack fundamental knowledge of neurotypical neonatal development and struggle to disentangle the effect of opioid exposure from other protective and risk factors impacting infant health. The fetal stage of brain development is a critical period when foundational aspects of brain structure and function are being established. In addition, postnatal brain development and specialization are shaped by environmental experiences thus allowing maturation to be influenced by lifestyle factors associated with opioid use. This Phase I project will plan for a large scale, multi- site research study to prospectively examine human brain, cognitive, behavioral, social, and emotional development beginning prenatally through childhood. New York University is one of four linked applications collaborating with investigators at Oregon Health and Sciences University, University of Pittsburgh Medical Center and University of Vermont. Together, we will address key challenges that are critical to the success of the planned Phase II study. Aim 1 will develop, implement and evaluate innovative recruitment and retention strategies for high-risk populations. We will measure the feasibility, throughput, and demographic characteristics associated with different recruitment methods through a longitudinal survey of 150 pregnant women per site (n=600 across sites), half of whom use opioids during pregnancy. Aim 2 will implement a multi- site, standardized, longitudinal research protocol by enrolling 20 pregnant women per site (n=80 across sites), half of whom use opioids during pregnancy. This prospective longitudinal study will collect fetal and neonatal multi-modal MRI, biospecimens, and maternal psychosocial and health assessments. Aim 3 will evaluate innovative MRI acquisition and processing strategies and statistical considerations intended to address key Phase II goals, including optimal measurement strategies and cross-site harmonization. Specifically, we will (a) evaluate strategies for cross-scanner and cross-time image harmonization; (b) test real-time evaluation of MRI data quality/motion during acquisition; (c) test the efficacy of accelerated image acquisition sequences; and (d) build fetal and neonatal MRI processing pipelines. Our New York investigative team contributes extensive experience leading studies in patients with opioid addiction, fetuses exposed to opioids, and longitudinal cohort studies in pregnant patients, young children, and difficult to reach populations. We have directed multiple consortia, performed large-scale population studies, and conducted multimodal MRI, EEG, and ultrasound studies in fetuses, neonates, and children. Our prior expertise in longitudinal modelling of infant MRI data and MRI methodology development suits us well to lead Aim 3's image harmonization and fetal/neonatal processing pipeline development. Additionally, the New York City population brings much-needed diversity across race, ethnicity, nativity, and socioeconomic status to the linked collaborative applications.